Controlling means for fluid operated machine tools



Dec. 10,1946. H, o cu 2,412,284

CONTROLLING MEANS FOR FLUI D OPERATED MACHINE TOOLS 2 Shee ts-Shet 1 Filed Dec. 26 1945 112/ z) iz i f Dec. '10, 1946. A. H. ORCUTT 2,412,284

CONTROLLING MEANS FOR FLUID OPERATED MACHINE TOOLS Filed Dec. 26, 1 945 2 Sheets-Sheet 2 v Patented Dec. 10, 1946 CONTROLLING MEANS FOR FLUID OPERATED MACHINE TOOLS Arthur Hitchcock Orcutt, Shirley, near Birmingham, England, assignor to The Gear Grinding Company Limited, Shirley, near Birmingham,

England Application December 26. 1945, Serial No. 637,25 In Great Britain December 29, 1944 V This invention relates to fluid operated machine toolsof the kind in which a reciprocatory workor tool -carrying slide is movable on a horizontal bed by pressure of oil 01' other liquid in a cylinder containing a plunger. In such machine tools it is usual to provide on the machine a tappet adapted to be actuated by adjustable dogs on the slide at or near either limit of the movements of the slide, the tappet being adapted to actuate a stopping or reversing valve (herein termed a controlling valve) in the system associated with the cylinder. Also there is usually arranged with such a machine tool, means for regulating the rate of speed of the slide which means may be incorporated with the said. valve, or may consist of a separate valve or valves: It is well known 3 Claims. (01. 51233) valves in a control box It situated at the front. of

that when the slide operates at relatively high speed it tends to over-run its normal limits under momentum. Thus if the dogs are set to stop or reverse the motion of the slide at a given position when the slide is moved at its slow rate, the slide will often over-run that position with the same setting of the dogs when moved at its higher rate of speed. For some purposes it is important that the slide should be stopped or reversed at a given position independently of its rate of motion, and the object of the present invention is to enable this requirement to be met in a simple and satisfactory manner.

The invention comprises the combination of a tappet, and a connection between the said speed regulating means and the tappet whereby on moving the said means to the fast or slow position an appropriate change is made in the position of the tappet.

In the accompanying drawings:

Figure 1 is a front elevation of a spline shaft grinding machine provided with the invention.

Figures 2 and 3 are respectively front elevation and plan illustrating to a larger scale than Figure 1 the portion of the machine which embodies my invention.

To elucidate the purpose of the invention I will first describe briefly the main features of the machine shown in Figure 1. On the bed a of the machine is mounted a horizontal reciprocatory slide b which carries an indexing head 0 and a tail stock (1, the work piece 6 being carried by the parts 0 and :1. At the left hand end or the slide is mounter a trimmer f for periodically trimming the grinding wheel 7, the latter being carried on a vertically movable slide it which is adjustable by a hand wheel 1'. The slide is reciprocated by a plunger in a hydraulic cylinder (not shown), and the motive fluid is controlled by the machine. This box'contains a pair ofrotary valves whichserve to determine whether the machine shall be operated at a high or a low rate of speed. Levers m on the outer ends of the spindles q of these valves are operable by a hand lever n. The machine is intended for grinding longitudinal splines on the work piece. For au tomatically controlling the reciprocation of the slide (at the rate determined by the position of the hand lever 11), a pair of adjustable dogs 0 are secured on the front of the slide. These dogs actuate a tappet associatedv with a controlling valve (in this case a reversing valve) so that at the end of eachtravel of the slide the direction of action is automatically reversed.

It will be understood that when the slide travels at its high rate of speed it tends to overrun the position at which reversal of motion is required, as already explained. This condition is usually undesirable and in some cases must be prevented, especially when the splines extend along only a part of the length of the work piece, it being essential in this case that at either rate of speed the motion of the slide should be reversed at exactly the correct position. The purpose of the present invention is to enable this requirement to be satisfied in a convenient manner.

The mode of carrying out the invention on the machine shown in Figure 1 will now be described with reference to Figures 2 and 3 which illustrate the invention more fully than Figure 1. The valve levers m are interconnected by a link 10, and on one of the levers m is formed or secured a cam r. The hand lever n is connected to one of the levers m by a link Z. Also on the front of the valve box It is pivoted a lever s one end of which rests on the cam, this end being held in contact with the cam by a spring 15. The other end of the lever s is connected by a link u to a lever 22 pivotally mounted on the top of the box It. To the lever 'v is pivotally attached a tappet lever to carrying a pin :1: which serves as the tappet, the upper projecting end of the tappet pin being arranged in the path of the dogs 0. The lower end of the tappet pin :0, in this example, engages a connecting piece 1:; which is carried by and is transversely slidable on a slide bar 2, which is movable in the direction of its length as indicated by the arrow in Figure 3. This bar serves to actuate the controlling valve in any convenient manner. As the bar 2 and the controlling valve are already known, it is unnecessary for the present purpose to describe or illustrate them, it being sufiicient for the present purpose to understand that longitudinal movement of the bar 2 serves to operate the controlling valve. It will be noticed that each dog is formed with an inclined strikin fac andthe arrangement is such that when either dog strikes the upper end of the tappet pin :c' the latter is moved by the dog in the direction for moving the bar a in the appropriate direction. During each movement the lever w which carries the pin rocks about its pivotal QQn nection with the lever '11.

In the example illustrated it is required to. determine accurately the reversing positionof the slide when it is moving towards the left. When the machine is at rest the hand lever n occupies the position shown in the drawings, To obtain slow speed travel of theslide the lever n, is moved to the left. This causes the tappet pin to be moved to the right, thus bringing it to the appropriate position relatively to the right hand dog. To, obtain high speed travel the hand lever nvis moved further to, the left. This causes the tappet pin to be moved further to the right and so cause it to be struck by the right hand dog at a sufficiently earlier period in the travel of the slide to ensure that notwithstanding the increased momentum of the slide it will not over-run, but come to rest at the same position as when the slide was actuated at the slow rate.

By this invention the desired result is obtained in a very simple, convenient and reliable manner. The invention is not, however, restricted to-the example described. as the mechanical details may be modified to suit different requirements. Also it will be understood that whereas I have in the foregoing described a specific application of the invention to a spline shaft grinding i machine, it may be applied in essentially the same manner to gear wheel grinding and other o ms of fl id op ma i ,1 1

Having thus described my invention what'I claim as new and desireto secure byLetters Patent is: 7

1. In a variable speed fluid operated machine 'tool having a reciprocatory slide carrying dogs ing the tappet, and means interconnecting the cam and tappetlever,

3.. In amachine tool having the features specified in claim 1, the combination of a cam arranged in association with a leverof the speed regulating means, a lever operable by the cam, a tappet arranged in operative connection with the controlling valve, a' lever carrying the tappet, a lever carrying, the tappet lever, and a link interconnecting the last named lever with the lever which is operable by the cam.

ARTHUR HITCHCOCK oac r r; 

